The momentum theorem of classical hydrodynamics is applied to a scheme for controlled atmospheric convention within a vertical tube of large height and diameter, open at both ends, for which the name aerological accelerator was previously suggested by the writers. The interior thermodynamic process is conceived as being moist adiabatic, although departures from this ideal case must be considered. The condensation and consequent latent heat release renders unnecessary any external drive, save for a proper supply of moist air. As discussed previously by the writers, the most important practical application of the device is the production of fresh water for ordinary uses from atmospheric water vapor. A year of daily soundings from the aerological station at Brownsville, Texas, is analyzed to examine the probable success of the procedure. The theoretical results are encouraging, but a host of questions and problems remain. Various of these are commented upon, and suggestions are made for further investigation of them.